Internal combustion operated hammer

ABSTRACT

An internal combustion operated hammer operated by a onecylinder lifting motor, in which a driving rod directly drivingly connected to the motor piston and extending through the cylinder head of the motor linearly reciprocates in striking direction a striking mechanism which comprises parts resiliently cushioned with regard to each other, and in which a compressor located between the cylinder head and the striking mechanism furnishes scavenging air to scavenging air passage means in the tool.

United States Patent 1191 Uebel Sept. 10, 1974 INTERNAL COMBUSTION OPERATED 3,323,601 6/1967 Uebel 173/76 HAMMER 3,334,693 8/1967 Badcock. 173/116 X 3,570,608 3/1971 Erma 173/116 [75] Inventor: Philipp Uebel, Munich, Germany [73] Assignee: Wacker Werke KG., Munchen, Primary f Y Sutherland Germany Assistant Exammer-Wtlham F. Pate, III [2 iled Nov 14 1972 Attorney, Agent, or FirmWalter Becker [21] Appl. No.: 306,311 [57] ABSTRACT An internal combustion operated hammer operated by 52 us. 131. 173/75 173/116 a One-cylinder lifting which a driving rod [51] km CL I fi 9/00 rectly drivingly connected to the motor piston and ex- [58] Field 127, 128, tending through the cylinder head of the motor lin- 173/118 58 76 134 early reciprocates in striking direction a striking 5 5. 1 6 R mechanism which comprises parts resiliently cush- [56] References Cited 5 ioned with regard to each other, and in which a compressor located between the cylinder head and the UNITED STATES PATENTS striking mechanism furnishes scavenging air to scavaifsiangtugl. 173/139 x enging air passage means in the too], 2:854:962 10/1958 Bergman 173/139 x 8 Claims, 1 Drawing Figure INTERNAL COMBUSTION OPERATED HAMMER The present invention relates to an internal combustion operated hammer which is driven by a onecylinder lifting piston motor and in which a driving bar extending through the cylinder head and directly connected to the motor piston linearly reciprocates in striking direction a striking mechanism which is composed of parts cushioned relative to each other and operable to actuate the tool head. The said hammer also includes a lifting piston compressor for delivering scavenging air to the scavenging air passage provided in the tool.

One-cylinder lifting piston motors are well developed driving units which have proved highly satisfactory also with internal combustion actuated hammers, especially in view of their reliable operation. With internal com bustion actuated hammers of the above mentioned type it is possible in view of the direct coupling of the motor piston with the striking mechanism by means of a driving bar extending through the cylinder head, to build slender handy devices of relatively low weight in which no difficulties are encountered to place the center of gravity of the upper mass directly above the tool.

The coupling of motor piston and striking mechanism through the intervention of the driving bar extending through the cylinder head requires that the striking energy passes through the detour via flywheel mass of the motor from the motor piston to the striking mechanism, because the explosion stroke of the motor piston is directed opposite to the direction in which the striking step is effected. The degree of fluctuation of the motor is a critical factor because on one hand it must not exceed a certain value while on the other hand the possibility to reduce said degree of fluctuation by increasing the flywheel mass is limited in view of the inherent undesired increase in the weight of the hammer.

It is, therefore, an object of the present invention to provide an internal combustion operated hammer of the above mentioned general type which with a given magnitude of the flywheel mass will have a low degree of fluctuation.

This object and other objects and advantages of the invention will appear more clearly from the following specification, in connection with the accompanying drawing illustrating a longitudinal section through an internal combustion actuated hammer according to the present invention.

The hammer according to the present invention is characterized primarily in that a lifting piston compressor for delivering scavenging air to the scavenging air passage in the tool is located between the cylinder head and the striking mechanism while the piston of said hammer is mounted on the driving bar. With this design it is possible to permit the compression stroke of the compressor to coincide selectively wither with the suction stroke or with the explosion stroke of the motor or to split up the compression stroke of the compressor so that equal or unequal portions of the compression stroke of the compressor coincide with portions of said suction and explosion strokes of the motor. Depending on the requirements, the compressor piston is designed as single acting piston with the compression chamber arranged on one or the other side of said compressor piston or to design the compressor piston as double acting piston with compressor chambers at both sides of said piston. In other words, any desired fixed relationship between the motor piston stroke and the compressor piston stroke may be established according to the invention and also that relationship according to which the degree of fluctuation of the motor is reduced to a minimum.

Internal combustion operated hammers in which the stroke of a lifting piston compressor delivering the scavenging air is at a fixed ratio to the piston stroke of the motor driving said piston are known, but withthese heretofore known arrangements, this ratio is determined by the specific construction and is so fixed that the compression stroke of the compressor piston can coincide only with the suction stroke of the motor piston, which fact usually, and especially with heretofore known devices of the general type involved results in an increase in the degree of fluctuation. In contrast thereto with the internal combustion operated hammer according to the invention the fixed relationship between the energy absorption of the compressor and the energy delivery of the motor piston while considering the regularly occurring fixed displacement between the oscillating movement of the striking mechanism and the oscillating movement of the motor piston can be so arranged that the compressor receives directly from the motor piston the energy required for compressing the air, in other words, receives said energy at least during a portion of the explosion stroke and not via a detour through the flywheel mass. In this way, the degree of fluctuation of the motor will not be increased by the compressor but may over devices operating without compressor even be reduced.

The characteristic of the striking mechanism remains uneffected by the compressor which is as advantageous as the fact that the arrangement of the compressor according to the invention between the motor and the striking mechanism permits a particularly simple arrangement of the passage for conveying the compressed air from the compressor to the tool. It is particularly advantageous and in most instances sufficient for obtaining the desired low degree of fluctuation when in conformity with a further development of the invention, the compressor operates with a single acting piston and its compression chamber is located on that side of the compressor piston which faces away from the striking mechanism. In this connection, a further development of the invention consists in that the compressor piston has openings which extend therethrough and interconnect the cylinder chambers on both sides of said piston. These openings are adapted to be closed by a closure member when the compressor piston carries out the suction stroke, whereas said closure member frees said openings when the piston carries out its compression stroke. In view of the air being conveyed to the tool, it is particularly advantageous in this connection when the chamber adjacent the compressor piston on the side of the striking mechanism is open to the guiding cylinder of the striking mechanism, and if in the wall of said striking mechanism there are provided axially extending grooves through which the air compressed by the compressor passes by the striking mechanism to the tool.

With the above mentioned design, the entire chamber between the compressor piston and the tool is always under a pressure which is higher than the atmospheric pressure so that at no time will dust particles be able through the air passage in the tool to pass to the sliding surfaces of the compressor piston and striking mechanism.

Advantageously, the striking mechanism preferably has a striking piston which is slidable in the above mentioned guiding cylinder and also has a driving piston which is connected to the driving bar and acts as a plunger piston, said striking pistons and said driving piston being elastically coupled to each other by means of the air cushion entrapped in the striking piston below the driving piston.

According to a still further feature of the invention, the driving piston and the compressor piston consist of one piece, and the compressor piston and the striking mechanism are lubricated by oil vapors which escape from the motor cylinder along the driving bar.

Referring now to the drawing in detail, the arrangement shown therein comprises the motor generally designated l with a motor piston 1a, a connecting rod lb, flywheels la, a cylinder 1d, and the cylinder head 1e. Connected to the motor piston 1a is a driving bar 2. The arrangement shown in FIG. 1 furthermore comprises the hammer housing 3 and the compressor piston 4, which latter is connected to the driving bar 2. The striking mechanism is designated generally with the reference numeral and is adapted to act upon the tool 6.

The compressor piston 4 which is arranged on that end of the driving bar 2 which protrudes from the cylinder head 12 forms an integral piece with the driving piston 5a of the striking mechanism 5. The compressor piston 4 has bores 4a extending therethrough which are adapted to be closed by a valve plate 41) when the piston 4 moves downwardly with regard to the'drawing, whereas these openings 4a are opened again when the piston 4 moves upwardly.

The chamber 7a which is confined by the housing 3 and located between the compressor piston 4 and the cylinder head la forms the compressor chamber into which the air to be compressed is during the downward stroke of the piston 4 drawn in through an inlet opening 4c and during the subsequent upward stroke of the compressor piston 4 is compressed in said chamber 7a. The opening 4c has, of course, associated therewith a check valve (not shown) which permits the air to flow into chamber 7a through the opening 4c, but prevents the air from escaping toward the outside during the compression stroke through the opening 40. The compressed air will, during the compression stroke of the piston 4, pass through the open bores 4a into the chamber 7b below said piston 4 and from here'flows past the striking mechanism 5 into longitudinal grooves 8 provided in the inner wall of housing 3 to the tool 6 upon the head of which the striker piston 5b periodically impacts. Piston 5b is elastically coupled by an air cushion 9 to the driving piston 5a acting as plunger piston, said air cushion 9 being enclosed in the striker piston 5b below the driving piston 5a. A longitudinal groove 50 in the striker piston 5b brings about that the coupling between said piston 5b and the driving piston 50 is effected only when the tool 6 has somewhat lifted the striker piston so that with the free hanging tool the driving piston 50 operates in an idling stroke.

The compressor piston 4 places the entire chamber therebelow up to the tool 6 under a continuous slight over pressure so that an uninterrupted flushing flow through the passage 6a will be assured and thus no dust particles can pass through to the sliding surfaces on the striker mechanism 5 and cannot climb up on the compressor piston 4.

The axial passages 4a of the compressor piston 4 and the longitudinal grooves 8 in the housing inner wall passing past the striking mechanism 5 make it possible to lubricate all movable parts of the hammer by oil vapors which escape from the motor cylinder 1d along the driving bar 2.

With the above described internal combustion actuated hammer according to the invention, the compression stroke of the piston 4 coincides with the explosion stroke of the motor piston la so that the energy is directed from the motor piston 1a to the compressor piston 4, and not via the detour through flywheel disc 1c. As a result-thereof, the provision of the compressor does at least not increase the degree of fluctuation of the motor.

It is, of course, to be understood that the present invention is, by no means, limited to the particular showing in the drawing, but also comprises any modifications within the scope of the appended claims.

What I claim is:

1. An internal combustion operated hammer which includes: a housing, a single cylinder piston motor of the internal combustion type arranged within said housing, striking means located within said housing in axially spaced relationship to said motor, said motor comprising a cylinder with cylinder head and a driving rod connected directly to the piston of said motor and extending through said cylinder head, air compressor means interposed between said cylinder head and said striking means and comprising a compressor piston having one side thereof connected to said driving rod and also comprising a connecting rod connected to the other side of said compressor piston, said striking means including a cylinder slidably arranged within a portion of said housing and comprising impact means operable to strike a tool, said compressor piston having that side thereof which is connected to said connecting rod face away from said impact means, said striking means also including a piston reciprocable in said cylinder and connected to said connecting rod, and passage means for conveying flushing air divided out from said compressor means directly into said cylinder of said striking means.

2. An internal combustion operated hammer which includes: a housing, a single cylinder piston motor of the internal combustion type arranged within said housing, striking means located within said housing in axially spaced relationship to said motor, said motor comprising a cylinder with cylinder head and a driving rod connected to the piston of said motor and extending through said cylinder head, air compressor means interposed between said cylinder head and said striking means and comprising a compressor piston having one side thereof connected to said driving rod and also comprising a connecting rod connected to the other side of said compressor piston, said striking means including a cylinder slidably arranged within a portion of said housing and comprising impact means operable to strike a tool, said compressor piston having that side thereof which is connected to said connecting rod face away from said impact means, said striking means also including a piston reciprocable in said cylinder and connected to said connecting rod, passage means for conveying air from said compressor means into said cylinder of said striking means, said compressor piston being provided with bores extending therethrough in the axial direction of said piston, and closure means supported by the connecting rod of said compressor and operable to close said bores in response to said compressor piston carrying out its suction stroke and to free said bores in response to said compressor piston carrying out its compression stroke.

3. A hammer according to claim 2, in which said compressor means is a single acting compressor having its compression chamber located on that side of said compressor piston remote from said striking means.

4. A hammer according to claim 2, in which said passage means includes conduit means interconnecting axially opposite sides of the cylinder of said striking means.

5. A hammer according to claim 2, in which said cylinder of said striking means has its inner surface provided with conduit means extending from the compression chamber of said compressor means over a portion only of the inner axial length of said last mentioned cylinder, the cylinder of said compressor means having that end thereof closed which faces away from said piston head.

6. A hammer according to claim 2, in which said compressor piston and the piston reciprocable in the cylinder of said striking means as well as said connecting rod interconnecting same consist of a single integral piece.

7. A hammer according to claim 2, in which a portion of said housing forms the cylinder for said compressor head and thereby the compression chamber of said compressor.

8. An internal combustion operated hammer which includes: a housing, a single cylinder piston motor of the internal combustion type arranged within said housing, striking means located within said housing in axially spaced relationship to said motor, said motor comprising a cylinder with cylinder head and a driving rod connected to the piston of said motor and extending through said cylinder head, air compressor means interposed between said cylinder head and said striking means and comprising a compressor piston having one side thereof connected to said driving rod and also comprising a connecting rod connected to the other side of said compressor piston, said striking means including a cylinder slidably arranged within a portion of said housing and comprising impact means operable to strike a tool, said compressor piston having that side thereof which is connected to said connecting rod face away from said impact means, said striking means also including a piston reciprocable in said cylinder and connected to said connecting rod, and passage means for conveying air from said compressor means into said cylinder of said striking means, a portion of said housing forming the cylinder for said compressor head and thereby the compression chamber of said compressor, the play of said motor piston in the motor cylinder and the play of said driving rod in said cylinder head and the play of said compressor head in said compressor cylinder being such that the compressor piston and said striking means are lubricated by oil vapor escaping from said motor cylinder. 

1. An internal combustion operated hammer which includes: a housing, a single cylinder piston motor of the internal combustion type arranged within said housing, striking means located within said housing in axially spaced relationship to said motor, said motor comprising a cylinder with cylinder head and a driving rod connected directly to the piston of said motor and extending through said cylinder head, air compressor means interposed between said cylinder head and said striking means and comprising a compressor piston having one side thereof connected to said driving rod and also comprising a connecting rod connected to the other side of said compressor piston, said striking means including a cylinder slidably arranged within a portion of said housing and comprising impact means operable to strike a tool, said compressor piston having that side thereof which is connected to said connecting rod face away from said impact means, said striking means also including a piston reciprocable in said cylinder and connected to said connecting rod, and passage means for conveying flushing air divided out from said compressor means directly into said cylinder of said striking means.
 2. An internal combustion operated hammer which includes: a housing, a single cylinder piston motor of the internal combustion type arranged within said housing, striking means located within said housing in axially spaced relationship to said motor, said motor comprising a cylinder with cylinder head and a driving rod connected to the piston of said motor and extending through said cylinder head, air compressor means interposed between said cylinder head and said striking means and comprising a compressor piston having one side thereof connected to said driving rod and also comprising a connecting rod connected to the other side of said compressor piston, said striking means including a cylinder slidably arranged within a portion of said housing and comprising impact means operable to strike a tool, said compressor piston having that side thereof which is connected to said connecting rod face away from said impact means, said striking means also including a piston reciprocable in said cylinder and connected to said connecting rod, passage means for conveying air from said compressor means into said cylinder of said striking means, said compressor piston being provided with bores extending therethrough in the axial direction of said piston, and closure means supported by the connecting rod of said compressor and operable to close said bores in response to said compressor piston carrying out its suction stroke and to free said bores in response to said compressor piston carrying out its compression stroke.
 3. A hammer according to claim 2, in which said compressor means is a single acting compressor having its compression chamber located on that side of said compressor piston remote from said striking means.
 4. A hammer according to claim 2, in which said passage means includes conduit means interconnecting axially opposite sides of the cylinder of said striking means.
 5. A hammer according to claim 2, in which said cylinder of said striking means has its inner surface provided with conduit means extending from the compression chamber of said compressor means over a portion only of the inner axial length of said last mentioned cylinder, the cylinder of said compressor means hAving that end thereof closed which faces away from said piston head.
 6. A hammer according to claim 2, in which said compressor piston and the piston reciprocable in the cylinder of said striking means as well as said connecting rod interconnecting same consist of a single integral piece.
 7. A hammer according to claim 2, in which a portion of said housing forms the cylinder for said compressor head and thereby the compression chamber of said compressor.
 8. An internal combustion operated hammer which includes: a housing, a single cylinder piston motor of the internal combustion type arranged within said housing, striking means located within said housing in axially spaced relationship to said motor, said motor comprising a cylinder with cylinder head and a driving rod connected to the piston of said motor and extending through said cylinder head, air compressor means interposed between said cylinder head and said striking means and comprising a compressor piston having one side thereof connected to said driving rod and also comprising a connecting rod connected to the other side of said compressor piston, said striking means including a cylinder slidably arranged within a portion of said housing and comprising impact means operable to strike a tool, said compressor piston having that side thereof which is connected to said connecting rod face away from said impact means, said striking means also including a piston reciprocable in said cylinder and connected to said connecting rod, and passage means for conveying air from said compressor means into said cylinder of said striking means, a portion of said housing forming the cylinder for said compressor head and thereby the compression chamber of said compressor, the play of said motor piston in the motor cylinder and the play of said driving rod in said cylinder head and the play of said compressor head in said compressor cylinder being such that the compressor piston and said striking means are lubricated by oil vapor escaping from said motor cylinder. 